Patent Literature 1 discloses a hydrogen generation apparatus including: a reformer configured to generate a hydrogen-containing gas from a raw material gas (i.e., from a power-generating raw material); a raw material passage, through which the raw material gas supplied to the reformer flows; a pressure adjuster provided on the raw material passage and configured to drop the pressure of the raw material gas; a booster provided on the raw material passage and configured to increase the pressure of the raw material gas that has passed through the pressure adjuster; a hydrodesulfurizer provided on the raw material passage and configured to remove sulfur compounds from the raw material gas that has passed through the pressure adjuster; and a recycle passage, through which the hydrogen-containing gas generated by the reformer is supplied to the raw material passage at a position that is downstream of the pressure adjuster and upstream of the hydrodesulfurizer and the booster.
Patent Literature 2 discloses a solid oxide fuel cell system including: a fuel cell module; a fuel supply apparatus; a water supply apparatus; an air supply apparatus; a reformer; and a controller configured to control the fuel supply apparatus, the water supply apparatus, and the air supply apparatus, as well as extraction of electric power from the fuel cell module. The controller includes a shutdown stop circuit configured to perform a shutdown stop in a state where the temperature of a fuel cell stack is higher than oxidization-suppressing temperatures. The solid oxide fuel cell system is characterized by performing a temperature drop operation of discharging high-temperature air remaining at the cathode side during a period after the shutdown stop, in which period the anode-side pressure is sufficiently higher than the cathode-side pressure and no reverse flow of air to the anode side occurs.